The present invention relates to compounds having inhibitory activity against enzymes which have been implicated in the promotion of certain adverse health, skin, hair, and oral conditions. Such enzymes include, but are not limited to lipases, serine proteases, metalloproteases, cysteine proteases, and aspartic proteases. More specifically these enzymes include, for example, lipase, carboxypeptidase A, chymotrypsin, elastase, trypsin, and leucine aminopeptidase. The compounds are useful against a wide spectrum of conditions, including but not limited to, diaper rash, acne, periodontal disease, and obesity. The compounds also have utility as contraceptives and drug delivery systems.
Diaper rash is a common form of irritation and inflammation of those diapered areas of an infant's body. This condition is also referred to as diaper dermatitis, napkin dermatitis, napkin rash, and nappy rash. While certainly more common in infants, this condition is not limited to infants. Any individual who suffers from incontinence to the extent that the use of absorbent articles is required may develop this condition. Such individuals include newborns, the elderly, and those who are critically ill or are nonambulatory.
Diaper rash is a condition which, in its earliest stage, is a contact irritant dermatitis. The irritation of simple diaper rash results from the extended contact of skin with urine, feces, or both. While it is known that body waste contributes to the promotion of diaper rash, the precise component or components of the urine or feces responsible for the resulting irritation of the skin have not been conclusively identified. Among the most commonly accepted factors linked to diaper rash are ammonia, fecal enzymes, bacteria, the products of bacterial action, urine pH, overhydration, and Candida albicans.
There is significant evidence that fecal proteolytic and lipolytic enzymes are important in the onset of the skin irritation and inflammation resulting from such conditions as, for example, diaper rash. See, e.g., Buckingham, U.S. Pat. No. 4,556,560, 1985; Zimmerer, U.S. Pat. No. 4,657,537, 1987; Berg et al., U.S. Pat. No. 4,685,909, 1987; Jordan et al., U.S. Pat. No. 4,842,593, 1989; Buckingham et al., "Etiologic Factors in Diaper Dermatitis: The Role of Feces", Pediatric Dermatology, Vol. 3, pp. 107-112 (1986); and Anderson et al., "Fecal Enzymes: in vivo Human Skin Irritation", Contact Dermatitis, Vol. 30, pp. 152-158 (1994). Furthermore, these effects are likely promulgated if urine is present and or if the skin is occluded.
McFarlane et al., "Contribution of the Microflora to Proteolysis in the Human Large Intestine", Journal of Applied Bacteriology, Vol. 64 (1988) pp. 37-46, report that fecal microflora contribute significantly to the proteolytic activity of human feces, which suggests that a wide number of bacterial enzymes, including proteases, lipases and other esterases, may contribute to skin damage. Studies with inhibitors designed to inhibit the enzymatic activity of various classes of proteases showed that serine proteases, cysteine proteases, and metalloproteases were the most likely to be responsible for the overall proteolytic activity of feces. However, the relative contributions of the different types of proteolytic enzymes to skin damage remains largely unknown.
Currently, several intervention approaches designed to prevent or treat such skin conditions as diaper rash attempt to address multiple causes or important cofactors. Reducing skin hydration by frequent changing of diapers, moisture absorbing powders, superabsorbent materials, and improving air flow in diapers are well known approaches. The use of artificial barriers is also widely practiced. Typical is the use of a cream, ointment, lotion, or paste which provides some degree of protection against fecal or urine irritants, regardless of their specific nature. However, the barrier approach, while reducing access of irritants to the skin may be occlusive in itself and can be aesthetically unpleasing.
Although there appear to be multiple factors involved in the development of such conditions as diaper rash, it is likely that the physiological responses of the skin to the irritants, although complicated, may involve some common mechanisms. For example, it has been shown that the production of cytokines by skin cells is a common response to the presence of irritants or skin barrier (stratum comeum) perturbation. The principal cell type that appears to be involved in the production of cytokines is the keratinocyte, which is the cell type found directly beneath the stratum comeum and is the most likely to initially encounter an irritant. It has been demonstrated that the keratinocyte secretes a wide variety of different cytokines in response to irritants, including the proinflammatory cytokine interleukin 1-alpha (IL-1.alpha.). This cytokine, and others, induce a cascade of events which may eventually lead to the physiological appearance of erythema, papules, scaling, and ulceration, which are collectively described as diaper rash.
While certain compositions have been previously described for the treatment of diaper rash that include inhibitors of fecal urease, lipase and/or protease enzyme activity, the importance of a proactive regimen to prevent the initial cytokine response by keratinocytes leading to the inflammatory cascade has not been previously recognized. In particular, it has not been previously recognized that fecal enzymes play an important role in inducing the cytokine response of keratinocytes to irritants, and that inhibition of fecal enzymes provides a more specific means of preventing or treating diaper rash than has been previously disclosed.
The compounds, compositions, and methods of the present invention overcome the foregoing deficiencies by inhibiting enzymes which are, as described supra, implicated in the causation of such conditions as, for example, the skin damage and inflammation of diaper rash. The inventors herein have surprisingly discovered that the compounds of the present invention inhibit enzymes which have been implicated in the cause of such conditions as diaper rash. It has been discovered that the present compounds have inhibitory activity against proteolytic and/or lipolytic enzymes, including, but not limited to, lipase, carboxypeptidase A, chymotrypsin, elastase, trypsin, and/or leucine aminopeptidase. The present compounds inhibit these enzymes which reduces the irritant potential of the fecal agent.
Furthermore, the inventors have surprisingly discovered that the compounds of the present invention have limited absorption through skin, thereby greatly reducing potential systemic side effects. Accordingly, such compounds may be delivered topically to the skin through such delivery systems as, for example, the topsheet of a diaper, which enables the close proximity of the compounds with the skin.
Furthermore, the present inventors have discovered that the utility of the present compounds is not limited to the treatment and prevention of such conditions as diaper rash. The present compounds may also be useful in the treatment of obesity, acting by partial inhibition of lipase in the intestine. Therefore, the present compounds, due to their inhibitory activity and polymerically conjugated nature, may be particularly safe in this regard due to their limited absorption following oral ingestion.
The present compounds are also useful for the treatment of skin against such inflammatory conditions as, for example, acne. Without intending to be limited by theory, bacterial lipases break down triglycerides in the sebum to form free fatty acids which are known to irritate the follicular wall. The lipase inhibiting power of the present compounds prevents oil production and tissue irritation. Furthermore, inhibition of bacterial proteases by the compounds of the present invention also reduce irritation in the inflamed follicle because these compounds comprise a poly(alkylene oxide) moiety which facilitates penetration into the sebum.
While certain non-polymeric guanidine and amidine derivatives have been described as inhibitors of proteases, including trypsin, chymotrypsin, plasmin, kallikrein, thrombin, and acrosin, the compounds of the present invention have not been described in the literature. See. e.g., U.S. Pat. No. 5,622,984, Nakai et al.; European Patent Application 0,486,702, Kabushiki et al., 1992; U.S. Pat. No. 4,948,891, Schnur et al., 1990; and U.S. Pat. No. 4,454,338, Fujii et al., 1984. However, while the art is replete with such guanidino and amidino enzyme inhibitors, there appears to be no mention of the use of such inhibitors for the alleviation or prevention of diaper rash.
Moreover, while the conjugation of polymers with peptides, polypeptides, and certain small molecules is known, such conjugation has been achieved for widely varying purposes. For example, copolymers of amino acid residues or peptide sequences with poly(alkylene oxides) wherein the copolymer is conjugated with pharmaceutically active compounds has been described. Such conjugates are disclosed as being useful for enhancing the functionality of poly(alkylene oxides). See U.S. Pat. No. 5,455,027, Zalipsky et al., 1995. Another example is the conjugation of taxol with polymers, particularly poly(ethylene oxide). In this instance, conjugation is utilized to increase the water-solubility, and thus delivery, of the drug. The taxol moiety is ultimately hydrolyzed from an implanted gel containing the conjugate. See U.S. Pat. No. 5,648,506, Desai et al., 1997. As a further example, poly(ethylene oxide) conjugates of para-aminobenzamidine have been prepared for the purification of enzymes by affinity extraction. French Patent Application No. 2,252,351, Segard et al., 1973; and Takerkart, G., "Preparation and Properties of Organophilic Trypsin Macro-Inhibitors: Diamidino-.alpha., .omega.-Diphenylcarbamyl-Poly(Ethylene Glycol)", FEBS Letters, Vol. 42 pp. 214-217 (1974). See also, U.S. Pat. No. 5,162,307, Digenis et al., 1992; Bernkop-Schnurch et al., "Synthesis and Evaluation of a Modified Mucoadhesive Polymer Protecting from .alpha.-Chymotrypsinic Degradation", International Journal of Pharmaceutics, Vol. 146, pp. 247-254 (1997); Bernkop-Schnurch et al., "Development and Analysis of a Polymer Protecting from Luminal Enzymatic Degradation Caused by .alpha.-Chymotrypsin", Drug Development and Industrial Pharmacy, Vol. 23, pp. 733-740 (1997); and Bernkop-Schnurch et al., "Development and in vitro Evaluation of a Drug Delivery System Protecting from Trypsinic Degradation", International Journal of Pharmaceutics, Vol. 157, pp. 17-25 (1997).
Accordingly, the present inventors have surprisingly discovered that the compounds, compositions, and methods herein have broad-spectrum applicability and enzymatic activity, particularly against conditions wherein proteases and lipases have been implicated.